#include <iostream>
#include <algorithm>
#include <bitset>
#include <iomanip>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>
#include <string>
#include <vector>
#include <list>
#include <stack>
#include <map>
#include <set>
#include <queue>
#include <deque>

using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll> P;


int main()
{
    ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
    int t;
    cin>>t;
    while(t--)
    {
        ll a,b;
        cin>>a>>b;
        ll maxx,minn;
        if(a==b&&a>=2)
            cout<<"2 "<<a<<endl;

        else if(abs(a-b)<=1)
            cout<<"-1 -1"<<endl;
        else
        {
            maxx=abs(a-b);
            minn=maxx;
            for(ll i=2;i<=sqrt(maxx);i++)
            {
                if(maxx%i==0)
                {
                    minn=i;
                    break;
                }
            }
            cout<<minn<<" ";
            cout<<maxx<<endl;
        }
    }


    return 0;
}